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authorEric Dumazet <dada1@cosmosbay.com>2007-03-27 13:53:04 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-04-25 22:28:17 -0700
commitbe776281aee54626a474ba06f91926b98bdd180d (patch)
tree7f397daec3c52ca04267186450f290f5e0ea3c5f
parent35fc92a9deee0da6e35fdc3150bb134e58f2fd63 (diff)
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[NET]: inet_ehash_secret should be __read_mostly and set only once
There is a very tiny probability that build_ehash_secret() is called at the same time by different CPUS. Also, using __read_mostly is a must for inet_ehash_secret Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/af_inet.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b7b7278d801..45ced52c03d 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -218,13 +218,23 @@ out:
return err;
}
-u32 inet_ehash_secret;
+u32 inet_ehash_secret __read_mostly;
EXPORT_SYMBOL(inet_ehash_secret);
+/*
+ * inet_ehash_secret must be set exactly once
+ * Instead of using a dedicated spinlock, we (ab)use inetsw_lock
+ */
void build_ehash_secret(void)
{
- while (!inet_ehash_secret)
- get_random_bytes(&inet_ehash_secret, 4);
+ u32 rnd;
+ do {
+ get_random_bytes(&rnd, sizeof(rnd));
+ } while (rnd == 0);
+ spin_lock_bh(&inetsw_lock);
+ if (!inet_ehash_secret)
+ inet_ehash_secret = rnd;
+ spin_unlock_bh(&inetsw_lock);
}
EXPORT_SYMBOL(build_ehash_secret);